1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device and a method for manufacturing the same, in which a protrusion substantially opposes a column spacer to reduce contact area between the column spacer and its opposing substrate, and the protrusion may be formed of an organic material to minimize deformation of the column spacer.
2. Discussion of the Related Art
Demands for various display devices have increased along with the development of the information age. Accordingly, many efforts have been made to research and develop various flat display devices such as liquid crystal display (LCD), plasma display panel (PDP), electroluminescent display (ELD), and vacuum fluorescent display (VFD). Some types of flat display devices have already been implemented in various types of equipment.
Among the various flat display devices, liquid crystal display (LCD) devices have been most widely used due to advantages such as thin profile, lightness in weight, and low power consumption. Thus, LCD devices provide a preferred substitute over Cathode Ray Tube (CRT). In addition to mobile type LCD devices such as notebook computers, LCD devices have been developed for computer monitors and televisions to receive and display broadcasting signals.
In order to implement LCD devices in various fields as a preferred display, the key to developing LCD devices depends on whether they can produce a high quality picture, such as high resolution and high luminance with a large-sized screen, while still maintaining lightness in weight, a thin profile, and low power consumption.
Meanwhile, a spacer may be formed between first and second substrates of the aforementioned LCD device to maintain a constant gap for a liquid crystal layer.
The spacer may be a ball spacer or a column spacer, for example, depending on shape and other variables.
The ball spacer has a spherical shape, and may be dispersed on the first and second substrates. Also, the ball spacer moves rather freely even after the first and second substrates are bonded to each other. The ball spacer has a small contact area with the first and second substrates.
By contrast, the column spacer may be formed by an array process on the first substrate or the second substrate. The column spacer may be formed on a predetermined substrate in a column shape having a predetermined height. Therefore, the column spacer has a relatively great contact area with the first and second substrates.
Hereinafter, a related art LCD device provided with a column spacer will be described with reference to the accompanying drawings.
FIG. 1 is a sectional view illustrating a related art LCD device provided with a column spacer.
As shown in FIG. 1, the related art LCD device provided with a column spacer includes first and second substrates 30 and 40 opposing each other, a column spacer 20 formed between the first and second substrates 30 and 40, and a liquid crystal layer (not shown) filled between the first and second substrates 30 and 40.
The first substrate 30 includes a gate line 31 crossing a data line (not shown) to define a pixel region, a thin film transistor TFT formed at a crossing region of the gate line 31 and the data line, and a pixel electrode (not shown) formed in each pixel region.
The second substrate 40 includes a black matrix layer 41 corresponding to a region other than the pixel region, a stripe shaped color filter layer 42 corresponding to vertical pixel regions parallel with the data line, and a common electrode or an overcoat layer 43 formed on the color filter layer 42.
The column spacer 20 corresponds to a predetermined position above the gate line 31.
The first substrate 30 further includes a gate insulating layer 36 formed on the entire surface including the gate line 31, and a passivation layer 37 formed on the gate insulating layer 36.
FIGS. 2A and 2B are a plane view and a sectional view illustrating a touch defect of the related art LCD device provided with a column spacer.
As shown in FIGS. 2A and 2B, in the related art LCD device provided with the column spacer, if an LCD panel 10 is touched with a finger or instrument along a predetermined direction, a spot is generated on the touched portion. The spot is referred to as a touch spot or a touch defect because the spot is generated on the screen of the LCD panel.
It is noted that such a touch defect is caused by the frictional force generated by a large contact area between the column spacer 20 and its opposing first substrate 1. In other words, as shown in FIG. 2B, the column spacer 20 is in contact with the first substrate 1 to form a relatively large contact area unlike the ball spacer. Therefore, it takes a long time to restore the first and second substrates 1 and 2 which have been shifted, due to touching, from their original state. For this reason, the spot remains until the first and second substrates 1 and 2 are restored to their original state.
The aforementioned related art LCD device provided with the column spacer has the following problems.
First, when the LCD panel is touched with a finger or instrument, the black state of the panel becomes unbalanced. In other words, the substrate may be deformed by a load that deforms the substrate in a direction of a polarizing plate attached onto a surface (rear surface) of the LCD panel when the polarizing plate is contracted or relaxed due to surrounding humidity and temperature change. For this reason, alignment of the liquid crystals may be disturbed, and as a result, an unbalanced black state is caused. Also, the upper and lower substrates may be distorted in the range of about 20 μm to 100 μm by touch (rubbing) of the LCD panel. In this case, even after a finger is removed from the LCD panel after touching, the two substrates fail to restore to their original state due to surface tension between them, thereby continuing to generate light leakage. As a result, the black screen becomes unbalanced.
This is because the pulling load generated as the column spacer is closely attached onto its opposing substrate is greater than a restoring load needed to return the substrate to its original shape.